1. Technical Field of the Invention
This invention relates to telecommunication systems and, more particularly, to a system and method of handling emergency calls in a radio telecommunications network.
2. Description of Related Art
When a mobile subscriber initiates an emergency call such as a 911 call, the call is connected through a serving mobile switching center (MSC) to an end office (EO) known as a Public Safety Answering Point (PSAP). There may be situations in which the call is then prematurely disconnected. This may be due to the subscriber hanging up, loss of radio signal, border rescan problems, loss of the subscriber's mobile station (MS) during an attack, or other reasons. Current and previous versions of TR45.2 (PN 3581) state that under these circumstances, the serving MSC attempts to reestablish the call. In other words, the serving MSC pages for the MS, and if a page response is received, an alert signal is sent to the responding MS. If the alert signal is answered, the call is reconnected to the PSAP.
However, since fraud and cloning of MSs is becoming more widespread, there is an increasing likelihood that the wrong MS will respond to the page attempt when the serving MSC attempts to reestablish the call. For example, a fraudulently cloned MS may respond to the page attempt. If this occurs, the cloned MS rather than the valid emergency MS may be inadvertently connected to the PSAP. Alternatively, it is also possible that a cloned MS could initiate the emergency call which is then prematurely disconnected. When the serving MSC attempts to reestablish the call, a valid MS may respond to the page attempt. If this occurs, the valid MS rather than the emergency cloned MS may be inadvertently connected to the PSAP.
There are no known prior art teachings of a solution to the aforementioned deficiency and shortcoming. In order to overcome the disadvantage of existing solutions, it would be advantageous to have a system and method of handling emergency calls in a radio telecommunications network in which an emergency MS is reconnected to the PSAP following a premature disconnection. The invention would reduce the probability of connecting the wrong MS, but if the wrong MS is connected by mistake, the invention would implement procedures to locate and reconnect the correct emergency MS.